Anterior clinoid process | |
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Details | |
Identifiers | |
Latin | processus clinoideus anterior |
TA98 | A02.1.05.022 |
TA2 | 607 |
FMA | 54693 |
Anatomical terms of bone |
The anterior clinoid process is a posterior projection of the sphenoid bone at the junction of the medial end of either lesser wing of sphenoid bone with the body of sphenoid bone. The bilateral processes flank the sella turcica anteriorly.
The ACP is an important structure for cranial and endovascular surgical operations for several structures, including the pituitary gland and the internal carotid artery.
The anterior clinoid process is a pyramid-shaped bony projection of the lesser wing of the sphenoid bone and forms part of the lateral wall of the optic canal. Between each ACP lies the sella turcica, which holds the pituitary gland. Additionally, the ACP is part of the anterior roof of the cavernous sinus. The posterior and inferior portions of the ACP border the internal carotid artery. [1] [2]
The free border of the tentorium cerebelli extends anteriorly on either side beyond the attached border of the same side (which ends anteriorly at the posterior clinoid process) to ultimately end by attaching onto the anterior clinoid process. [1] [3]
The anterior clinoid process projects over the internal carotid artery, which supplies the majority of blood to the brain. Because of the "spear-like" shape of the ACP and the large size of this artery, it is possible (though rare) that as a complication of major head trauma, the ACP may puncture the vessel and cause intracranial hemorrhage. [4] Additionally, when an aneurysm forms below the ACP, the projection may create a flat or pointed area of compression that may rupture the vessel. [5]
More frequently, this positioning means that the ACP is an important surgical access point for correction of aneurysms, tumors, and other operations in the structures adjacent to it. It is particularly common for surgery to involve the ACP when operating on giant pituitary adenomas [2] and giant meningiomas, a type of meningioma which may originate at the ACP or spread to it from other structures. [6]
Endovascular surgery has become an increasingly common procedure for lesions and aneurysms around the ACP, as the complex anatomy makes it difficult and dangerous to access via other surgical methods. However, endovascular surgery in the clinoid region is also relatively high-risk, so only serious injuries and diseases are indicated for this procedure. [2] [7]
The anterior and posterior clinoid processes surround the sella turcica like the four corners of a four poster bed. Cline is Greek for bed. –oid, as usual, indicates a similarity to. [8] The term may also come from the Greek root klinein or the Latin clinare, both meaning "sloped" as in "inclined".
The sphenoid bone is an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the basilar part of the occipital bone. The sphenoid bone is one of the seven bones that articulate to form the orbit. Its shape somewhat resembles that of a butterfly or bat with its wings extended.
The internal carotid artery is an artery in the neck which supplies the anterior and middle cerebral circulation.
The sella turcica is a saddle-shaped depression in the body of the sphenoid bone of the human skull and of the skulls of other hominids including chimpanzees, gorillas and orangutans. It serves as a cephalometric landmark. The pituitary gland or hypophysis is located within the most inferior aspect of the sella turcica, the hypophyseal fossa.
Cerebral angiography is a form of angiography which provides images of blood vessels in and around the brain, thereby allowing detection of abnormalities such as arteriovenous malformations and aneurysms. It was pioneered in 1927 by the Portuguese neurologist Egas Moniz at the University of Lisbon, who also helped develop thorotrast for use in the procedure.
The foramen lacerum is a triangular hole in the base of skull. It is located between the sphenoid bone, the apex of the petrous part of the temporal bone, and the basilar part of the occipital bone.
In human anatomy, the left and right posterior communicating arteries are small arteries at the base of the brain that form part of the circle of Willis.
The cavernous sinus within the human head is one of the dural venous sinuses creating a cavity called the lateral sellar compartment bordered by the temporal bone of the skull and the sphenoid bone, lateral to the sella turcica.
The foramen spinosum is a small open hole in the greater wing of the sphenoid bone that gives passage to the middle meningeal artery and vein, and the meningeal branch of the mandibular nerve.
The sphenoid sinus is a paired paranasal sinus occurring within the body of the sphenoid bone. It represents one pair of the four paired paranasal sinuses. The pair of sphenoid sinuses are separated in the middle by a septum of sphenoid sinuses. Each sphenoid sinus communicates with the nasal cavity via the opening of sphenoidal sinus. The two sphenoid sinuses vary in size and shape, and are usually asymmetrical.
The lesser wings of the sphenoid or orbito-sphenoids are two thin triangular plates, which arise from the upper and anterior parts of the body, and, projecting lateralward, end in sharp points [Fig. 1].
The middle cranial fossa is formed by the sphenoid bones, and the temporal bones. It lodges the temporal lobes, and the pituitary gland. It is deeper than the anterior cranial fossa, is narrow medially and widens laterally to the sides of the skull. It is separated from the posterior cranial fossa by the clivus and the petrous crest.
The infratemporal fossa is an irregularly shaped cavity that is a part of the skull. It is situated below and medial to the zygomatic arch. It is not fully enclosed by bone in all directions. It contains superficial muscles, including the lower part of the temporalis muscle, the lateral pterygoid muscle, and the medial pterygoid muscle. It also contains important blood vessels such as the middle meningeal artery, the pterygoid plexus, and the retromandibular vein, and nerves such as the mandibular nerve (CN V3) and its branches.
The dorsum sellae is part of the sphenoid bone in the skull. Together with the basilar part of the occipital bone it forms the clivus.
The tuberculum sellae is a slight median elevation upon the superior aspect of the body of sphenoid bone at the anterior boundary of the sella turcica and posterior boundary of the chiasmatic groove. A middle clinoid process flanks the tuberculum sellae on either side.
The posterior clinoid processes are the tubercles of the sphenoid bone situated at the superior angles of the dorsum sellæ which represents the posterior boundary of the sella turcica. They vary considerably in size and form. The posterior clinoid processes deepen the sella turcica, and give attachment to the tentorium cerebelli, and the dura forming the floor of the hypophyseal fossa.
The body of the sphenoid bone, more or less cubical in shape, is hollowed out in its interior to form two large cavities, the sphenoidal sinuses, which are separated from each other by a septum.
Chiasmal syndrome is the set of signs and symptoms that are associated with lesions of the optic chiasm, manifesting as various impairments of the affected's visual field according to the location of the lesion along the optic nerve. Pituitary adenomas are the most common cause; however, chiasmal syndrome may be caused by cancer, or associated with other medical conditions such as multiple sclerosis and neurofibromatosis.
The base of skull, also known as the cranial base or the cranial floor, is the most inferior area of the skull. It is composed of the endocranium and the lower parts of the calvaria.
Interventional neuroradiology (INR) also known as neurointerventional surgery (NIS), endovascular therapy (EVT), endovascular neurosurgery, and interventional neurology is a medical subspecialty of neurosurgery, neuroradiology, intervention radiology and neurology specializing in minimally invasive image-based technologies and procedures used in diagnosis and treatment of diseases of the head, neck, and spine.
Endoscopic endonasal surgery is a minimally invasive technique used mainly in neurosurgery and otolaryngology. A neurosurgeon or an otolaryngologist, using an endoscope that is entered through the nose, fixes or removes brain defects or tumors in the anterior skull base. Normally an otolaryngologist performs the initial stage of surgery through the nasal cavity and sphenoid bone; a neurosurgeon performs the rest of the surgery involving drilling into any cavities containing a neural organ such as the pituitary gland. The use of endoscope was first introduced in Transsphenoidal Pituitary Surgery by R Jankowsky, J Auque, C Simon et al. in 1992 G.
This article incorporates text in the public domain from page 151 of the 20th edition of Gray's Anatomy (1918)